Waving a chromed semiautomatic pistol, the robber pushed into the building in the bustling Five Points neighborhood of Columbia, S.C., just before 11 p.m. on April 11, 2009. “Gimme what you got!” he yelled, his gun hand trembling.

Attorney Jim Corley was one of four people in the room, the lounge area of a 12-step recovery group’s meeting hall. “He said, ‘Give me your wallet,’” Corley recalled. “So I reached around to my back pocket and gave him what was there.”

Unfortunately for the gunman, later identified as Kayson Helms, 18, of Edison, N.J., that was Corley’s tiny Kel-Tec .32, hidden in a wallet holster and loaded with a half-dozen hollow points. Corley fired once into the robber’s abdomen. The young man turned. Corley fired twice more, hitting him in the neck and again in the torso. Helms ran into the night and collapsed to die on a railroad embankment 100 feet away.

Reports filed by officers who arrived at the scene a short time later called it an “exceptionally clear” case of justifiable homicide. Following South Carolina’s “Castle Doctrine,” which allows the use of deadly force in self-defense, police did not arrest Corley. They did not interrogate him. Corley was offered the opportunity to make a voluntary statement, which he did.

Helms’ friends and relatives were left to mourn, barred by the same Castle Doctrine from filing a civil lawsuit.

Jim Corley became an unintentional spokesman for a burgeoning movement of millions of Americans who secretly and legally pack pistols in waistbands, under jackets, strapped to ankles, stashed in purses or — like Corley — tucked in hip pockets.

From its beginnings in the 1980s, the “right-to-carry” movement has succeeded in boosting the number of licensed concealed-gun carriers from fewer than 1 million to a record 6 million today, according to estimates from gun-rights groups that are supported by msnbc.com’s research. And while hotly debated, the effect of this dramatic increase is largely unknown.

Gun enthusiasts claim a link between more private citizens carrying concealed weapons and the nation’s dramatic decrease in violent crime. Gun-control activists argue that concealed-carry permits are being handed out to people who should never get them, sometimes resulting in tragic, needless shootings.

Effect on crime is hotly debatedBut even with the push to expand concealed-carry rights now in its third decade, no scientific studies have reached any widely accepted conclusions about the movement’s effect on crime or personal safety.

Statistics from the national Centers for Disease Control do indicate that the murder and mayhem predicted by many opponents of concealed-carry laws have not come to pass. But even that point, while celebrated by gun-rights activists and conceded by some concealed-carry opponents, is disputed by others.

Both sides do agree on one thing: More Americans than ever are carrying hidden guns.

Firearms laws have been growing more relaxed across the United States for years. Gun-control activists have failed in efforts to re-enact the nationwide ban on certain semiautomatic rifles they call “assault weapons.” They were unable to block a change in federal law, signed by President Obama this year, which allows guns to be carried in national parks. And they watched in dismay as the U.S. Supreme Court ruled in June 2008 that the Second Amendment grants residents of Washington, D.C., the right to own and keep loaded handguns in their homes.

“We’ve had a very good run,” said Andrew Arulanandam, chief spokesman for the 4 million-member National Rifle Association, the nation’s largest and most powerful voice for gun rights.

It’s a run that has often been paced by the work of the NRA and its allies on concealed-weapons laws.

Going For Their GunsIn a little more than 20 years, the concealed-carry movement has won changes in scores of laws across the nation to boost from nine to 37 the number of “shall issue” states in which civilians must be given concealed-carry permits, known as CCWs, generally if they are 21 or older, do not have a criminal record and are willing to submit to fingerprinting and a background check. In two more states, Alaska and Vermont, most adults may carry concealed handguns without obtaining permits.

The movement's successes have energized some gun-rights activists to push for laws that further increase their ability to carry weapons, even when those laws trump private property and states’ rights.

The reasons for the push to loosen concealed carry laws are themselves open to debate.

Kristen Rand, legislative director for the Violence Policy Center, a gun-control group, said the movement “has to do with selling more guns.” While it was pushed by groups like the NRA, it also “dovetailed with the gun industry’s desperate need to find a new market.”

“Their efforts at reaching out to minorities and women have failed,” said Rand, whose group advocates banning all handguns and some rifles but believes sporting rifles and shotguns should remain legal. “The industry constantly has to look for a way to make a guy who already owns 15 guns buy a new one.”

But Alan Gottlieb, president of the Second Amendment Foundation, which promotes and defends gun rights, said the movement has been a grass-roots drive.

As he built his Bellevue, Wash.-based organization from its start in 1974 to its membership of 600,000 today, he constantly polled members for direction. Each time, he said, they responded with a clear message: “‘I want the right to carry.’ That was the single biggest thing everyone wanted.”

When Gottlieb’s foundation got its start, just four states allowed regular citizens to carry concealed weapons simply because they wanted to.

Some other states were known as “may issue,” meaning concealed weapons permits were dispensed at the discretion of state or local law enforcement officials. That system often was dogged by charges of political favoritism, and it continues to be in states such as California and New York, where it is still in place.

And many states did not allow civilians to carry concealed weapons under any circumstances, as is still the case in Illinois and Wisconsin.

While four states joined the “shall issue” ranks through the early and mid-1980s, the movement’s turning point came in 1987, when a successful “shall-issue” campaign in Florida received heavy national media coverage.

The publicity had a snowball effect, according to Gottlieb. By 1990, there were 15 “shall-issue” states and by 2000, there were 30.

The NRA’s Arulanandam said the movement gained even more momentum in the wake of Hurricane Katrina in 2005.

“People saw it live, they saw people taking trash cans and throwing them through store windows right in front of TV cameras,” he said. “People processed these images, and they processed these events, and they realized that when the unthinkable happens, they want to have an effective means of defending themselves and their loved ones.”

While gun-rights and gun-control activists argue about what led to the loosening of concealed-weapons laws, they agree that the lobbying prowess of groups like Gottlieb’s and Arulanandam’s helped make it happen.

“We are tenacious and we work hard to pass whatever our legislative agenda is,” Arulanandam said.

“Tactically, they’ve been brilliant on a lot of issues,” agreed Paul Helmke of the Brady Campaign to Prevent Gun Violence, perhaps the nation’s best-known gun-control advocacy group, which opposes "shall-issue" concealed-weapons laws but does not advocate a ban on handguns.

The concealed-carry movement also has been aided by a fractured opposition, said Jim Kessler of the progressive think tank Third Way, who has been advocating gun-control measures for years. “The gun safety movement is splintered. … They have different issues and they fight each other.”

Indeed, gun-control advocates are often at odds over such basics as the effect of relaxed concealed-carry laws on crime.

Nationwide statistics aren't availableRand, the spokeswoman for the Violence Policy Center, acknowledged that “we don’t have centralized data-gathering to know what people are doing with these licenses.”

“(But) anecdotally, we know they’re doing quite a bit of harm,” she said.

Her group posts news accounts of concealed-weapons permit holders allegedly involved in firearms deaths on a part of its Web site called “Concealed Carry Killers.” The site says 130 civilians and nine police officers have been killed and 13 mass shootings have been carried out by people with concealed-weapons permits since May 2007. Helmke, of the Brady Campaign, cited the work of Rand’s group in a recent blog post that mocked the NRA for saying concealed weapons permit holders “are all ‘law-abiding’ citizens.’”

But Third Way’s Kessler, while agreeing there is “no evidence” that more concealed-weapons permits have led to lower crime rates, said, “I’ve not seen any evidence on the other side that it creates havoc either.”

Gun-rights activists point to studies they say prove that having more guns in civilian hands, whether being carried by permit holders or not, has reduced crime rates.

“Firearms in the hands of law abiding citizens prevent 1 million robberies, murders and rapes every year,” said John Pierce, a Virginia-based gun-rights activist with opencarry.org. That’s at least partly due to the huge increase in “shall-issue” states, which has been “the most significant beneficial public policy move in my lifetime,” said the 41-year-old Pierce.

But Dr. David Hemenway, Ph.D., a Harvard professor of public health who has studied gun violence for years, said that when it comes to concealed-carry laws, neither side can make a legitimate claim about their effects on crime.

Hemenway said that the most definitive review to date — a 2004 look at research on the topic by the National Research Council — “found no credible evidence that passage of right-to-carry laws increases or decreases violent crime.”

In the 1980s and ’90s, as the concealed-carry movement gained steam, Americans were killed by others with guns at the rate of about 5.66 per 100,000 population. In this decade, the rate has fallen to just over 4.07 per 100,000, a 28 percent drop. The decline follows a fivefold increase in the number of “shall-issue” and unrestricted concealed-carry states from 1986 to 2006.

The highest gun homicide rate is in Washington, D.C., which has had the nation’s strictest gun-control laws for years and bans concealed carry: 20.50 deaths per 100,000 population, five times the general rate. The lowest rate, 1.12, is in Utah, which has such a liberal concealed weapons policy that most American adults can get a permit to carry a gun in Utah without even visiting the state.

The decline in gun homicides also comes as U.S. firearm sales are skyrocketing, according to federal background checks that are required for most gun sales. After holding stable at 8.5 to 9 million checks from 1999 to 2005, the FBI reported a surge to 10 million in 2006, 11 million in 2007, nearly 13 million in 2008 and more than 14 million last year, a 55 percent increase in just four years.

Because the gun death rates parallel an overall drop in crime, Hemenway suspects that the decline “has nothing to do with concealed-carry laws.”

While other researchers point to numerous, complex reasons for fluctuations in the crime rate, Hemenway said the surge that began in the 1980s and the subsequent decline were "all about inner-city gun crime." Crime "declined nationwide after the crack wars died out," Rand agreed.

Hemenway said valid studies of the effects of more concealed weapons permits on firearms deaths could only be obtained by studying shooting deaths that involved concealed-carry permit holders.

But such data is not collected by most law enforcement agencies and not compiled nationally, said Rand of the Violence Policy Center. Her group would like to see nationwide reporting of the number of concealed-weapons permit holders, a “systematic collection of arrest and conviction data” for them as well as hard data on the number of justifiable homicides they’re involved in.

But “the NRA and the gun lobby would never allow that,” Rand charged. “The gun lobby is trying to keep all this data secret. … They know it’s not going to go well for them.”

The NRA’s Arulanandam denied that the organization universally opposes the collection of such data, but said it would not endorse the concept without seeing a specific proposal in writing.

Meanwhile, the NRA and its allies continue to push for even fewer restrictions on where civilians can carry concealed weapons, in some cases provoking charges that they are trying to place gun rights above other fundamental rights.

They fell just two votes shy of winning approval in the U.S. Senate last summer of a measure that would have guaranteed state-to-state reciprocity for all concealed-carry laws. The Thune amendment, named for sponsoring Sen. John Thune, R-S.D., would have automatically allowed a permit holder from one state to carry a concealed gun in all states that issue such permits.

Currently, reciprocal arrangements are left to the states, and critics of the Thune amendment labeled it a trampling of states’ rights because it would have forced one state’s training and other standards on states that may have tougher rules.

“I think a lot of senators did not understand that if Florida gives someone a concealed-carry permit and they have a criminal record a mile long, you’ve got to let them carry in your state,” Rand said. “I think that’s why you haven’t seen it come back up. … People are seeing it as more of a states’ rights issue.”

Even some gun-rights enthusiasts like Pierce agree with that. “It would have been wonderful for the 6 million permit holders across the country, but ultimately I think it would have been constitutionally unsupportable,” he said.

But others, including Gottlieb of the Second Amendment Foundation and Arulanandam of the NRA, say gun-control advocates had no such concern for states’ rights when they pushed for federal laws to ban specific weapons and mandate background checks. They foresee that argument crumbling and say it’s only a matter of time before right-to-carry reciprocity is the law of the land.

2nd Amendment vs. property rightsAnother front in the push to expand concealed-carry rights involves private property. In most states, property owners are free to bar concealed-gun carriers. But gun-rights activists say that goes too far when it extends to firearms locked in private vehicles. The NRA successfully helped defend Oklahoma laws that prohibit banning guns in private parking lots and has tackled the issue in other states.

Arulanandam said the parking lot fight was actually started by gun-control groups who encouraged employers across the country to search workers’ vehicles and fire those caught with guns, often outdoorsmen planning to go hunting before or after work. Once gun-control forces made it an issue, the NRA responded, he said.

Rand said such comments are double-talk from “cynical” NRA leaders who are more interested in fear-mongering and fund-raising than constitutional rights.

“The idea that you send people out into public and if someone else has a gun, you have to kill them, that becomes anarchy,” she said.

But Jim Corley, the Columbia, S.C., attorney whose three squeezes of the trigger of his Kel-Tec .32 ended the life of would-be robber Kayson Helms, says he’ll stick with his gun.

“I was glad I was legally able to carry,” said Corley, 61, unemotionally, in the gravelly voice of a three-pack-a-day smoker. “I did what had to be done under the circumstances at the time. If it happened again today, I’d do the exact same thing.”